Q

APES 6.9 Hydroelectric Power

Enduring Understanding:

  • Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective:

  • Describe the use of hydroelectricity in power generation.
  • Describe the effects of the use of hydroelectricity in power generation on the environment.

Essential Knowledge:

  • Hydroelectric power can be generated in several ways.  Dams built across rivers collect water in reservoirs.  The moving water can be used to spin a turbine.  Turbines can also be placed in small rivers, where the flowing water spins the turbine.
  • Tidal energy uses the energy produced by tidal flows to turn a turbine.
  • Hydroelectric power does not generate air pollution or waste, but construction of the power plants can be expensive, and there may be a loss of or change in habitats following the construction of dams.

Sources

Dams and Reservoirs

  • Relies on the kinetic energy of moving water
  • The reservoir is is the body of water contained behind the dam
  • The intake is the opening into the narrow ‘penstock,’ where water flows and gains speed
  • It then flows past a turbine, turning it, and generating electricity
  • The water flows past unaffected and continues into a river or another body of water

Micro Hydropower

  • Small scale
  • Water is taken into an intake but transported in pipes through the penstock
  • The powerhouse is right on the bank, water flows through then empties back into the main river
  • Off the grid but same process

Tidal Power

  • Uses the same principles, but in the ocean
  • The current or tides turn the turbine which generates electricity

Advantages and Disadvantages

Benefits

  • No air pollution
  • No waste
  • Relatively inexpensive electricity generation
  • Additional services provided be reservoir

Drawbacks

  • Flooding of land to make reservoir
  • Disruption to flow rates of river
  • High maintenance cost for tidal
  • High construction cost for dams
  • Most viable sites are already used

Environmental Concerns

  • There is a ton of habitat destruction or at least change when reservoirs are created
    • Disrupting the flow of water creates massive changes, happening to rapidly that natural adaptation cannot keep up
  • Fish migrations are also disrupted
    • In North America there have been some investments in ‘fish ladders’ where the fish can gently move up without encountering any of the turbines or mechanics